Contact clip



July 20, 1948. M. M. CLAYTON CONTACT CLIP Filed April 11, 1945 INVEN TOR Mar/1'0 M. (Yu /fol? a. 91%

IITTORNEY increased certainty of Patented July 20, 1948 NM'E STATES PATENT OFFHCE CONTACT CLIP Martin M. Clayton, Enon Valley, Pa., assignor to National Electric Products Corporation, Am bridge, Pa., a corporation of Delaware Application April 11, 1945, Serial No. 587,752

(or. ire-s34) 8 Claims.

This invention relates .to a contact clip for organization in an assembly of conductor wire and contact clip in a receptacle to make electrical contact between the conductor wire and the prong of an attachment plug.

In my prior Patent No. 2,119,777, dated June '7, 1938, I disclose an organization which avoids numerous disadvantageous features incident to prior assemblies of like nature. In it a contact clip of U-shape and adapted to receive the prong of an attachment plug between its-legs is inserted in the cavity or chamber of a receptacle, and one leg of the contact clip is bonded at its terminal end and on its outer surface in embracing engagement with a conductor wire. By this organization I have avoided the undesirable feature of engaging the conductor wire to the contact clip by means of a binding screw, and also have avoided the expedient of clamping the contact clip to the conductor by pressure exerted by two separate parts of a receptacle urged into clamping relation on the contact clip and the conductor by means of set screws. It has been noted that in the organization of my said. prior patent one leg of the contact clip is bonded to the conductor as by soldering or welding. In such organization welding of necessity and soldering as a matter of practical convenience is done in factory preparation by which the conductors have contact clips mounted thereon in spaced relation and by bonded integration.

Thus in such an organization the spacing of outlet receptacles cannot be made wholly at will in the field, being limited to the spacing of clips along the conductor predetermined by factory operation. Whereas a bonded integration gives permanence in maintaining good electrical contact at the receptacle as compared with .the use of binding screws to secure the contact clip and conductor in conductive relation and as compared with the use of a set screw to urge together two clamping parts of a receptacle, if such bonded integration should be broken in installation or service the result is to give poor electrical contact at the receptacle.

The object of my present invention, which is to combine the advantages of my above noted patent with flexibility of installation in the field such that in the field outlets may be placed at will in sequentially spaced relationship or in isolated positions and with increased certainty of good contact conditions, results from my discovery that the use of a novel form and arrangement of contact clip will give an unbonded engagement of the contact clip with the wire which produces 2 a continuing electrical contact superior to that obtained by bonded integration.

Thus I have discovered that I am able to mount my contact clip on a conductor wire to stand in a receptacle in such relation that the entry of a contact prong between the legs, or leaves, of the clip serves to tighten and perfect electrical contact between the clip and the conductor on which it is mounted. In an organization including contact clips in accordance with my invention I am able to give an extended utility over that of my prior patent in that the organization is not limited to runs of raceway such as multiple outlet duct, but that it is adapted to receptacles of all sorts positioned at will throughout a wiring installation. As compared 'With prior art structures in which the receptacles are of extended size and specialized shape in order to provide for binding screws or otherwise to bind the contact clip and conductor in electrical contact, I am able to use in any association a receptacle of the smallest size and simplest form, such as those I pre-' viously have installed in multiple outlet ducts.

An additional object attained by my invention is that in my organization of conductor and contact clips in unbonded electrical contact with each other there is in use of the device sufficient relative movement to maintain the contactin surfaces of the metal in clean, untarnished condition, giving maximum electrical conductivity therebetween.

In the accompanying drawings exemplary of my invention Fig. I is a perspective view of the preferred form of my prong-contacting element or clip.

' Fig. II is a similar perspective view showing the contact element or clip of Fig. I snapped into position on a stripped region of an insulated conductor.

Fig. III is a fragmentary vertical sectional view showing one-half of a receptacle structure with a contact clip in the chamber or cavity thereof in mounted position on a conductor wire, the structure of the contact clip being as normally arranged without the insertion of the prong of an attachment plug into the clip.

Fig. IV is a similar view showing the same orplified form and minimum size previously utilized in multiple outlet duct.

Fig. VI is a phantom view of a duplex receptacle of the sort installed in isolated positions rather than in a raceway, and which consists essentially of two of the receptacles shown in Fig. V.

In the drawings, reference letter A designates a contact clip embodying the structural principles of my invention. As shown the contact clip is of the bow-spring type having its bight l with expanded side-walls at the base of the structure, and with approximately parallel side-leaves or legs 2 and 3 extended upwardly from the bight. At its upper end leaf 2 is curved outwardly at 4 to provide smooth entry of a contact prong between it and its associated leaf 3, and to bear against the wall of a receptacle cavity in which the spring clip is housed.

The other leaf 3 of the clip at its upper end is curved outwardly to provide a primarily cylindrical bow-spring wire-embracing portion. At the lower and outer region of this bow-spring 5 the leaf is reversely curved at 6 to approach the outer surface of the upright reach of the leaf. Desirably this reverse curve is extended toward the leaf such distance that the space between the post surface thus provided is less than the diameter of the approximately cylindrical bow-spring portion 5, so that the entry into the interior of bow-spring 5 is of lesser width than the diameter of a conductor wire closely embraced within the bowspring. From reverse curve 6 a wing 1 extends outwardly and away from the main upward reach of the leaf 3. This wing, which provides the wallcontacting element of leaf 3, performs in use of the clip a function of great importance.

The foregoing describes the contact clip itself as shown in Fig. I of the drawings. In Fig. II of the drawings the contact clip is shown applied to the bared region of a conductor wire B, the clip having been snapped into position on the wire in such manner that the primarily cylindrical bowspring portion 5 of leaf 3 embraces the conductor wire. In snapping the clip onto the wire, the wire entering between the upright reach of the leaf and the reverse curve 6 thereof forces projecting wing 1 outwardly a short distance, and forms a relatively rigid backing for the wing.

Fig. III of the drawings shows a contact clip and its associated conductor wire B installed in the chamber C of a receptacle D formed in one piece of suitable insulating material, such as plastic composition with an insulating bottom closure Id. As so installed the outwardly deflected upper edge of leaf 2 lies against wall 2c of the receptacle cavity-and the outer edge of wing 1, bears against the wall 30 of the chamber. The prong-receiving space 8 between leaves 2 and 3 stands in alignment with prong-receiving opening 2d in the upper wall 3d of the receptacle in position to receive the contact prong of an attachment plug.

As the clip is installed, wing 1 of leaf 3 is tensioned against wall 3c, so that the contact clip is held firmly in the chamber 0 independently of bottom closure Id, and the conductor wire is secured and positioned in the cavity. Also, the structure of the contact clip is such that with the end of one leaf bearing against one fixed wall of the receptacle chamber, the resilient wing on the other leaf bearing against the opposite chamber wall determines the effective shape of the clip. Thus the clip having its primary dimensions, such as length of leaf and length of wing apportioned to the chamber dimensions of the receptacle in which the clip is to be used, mere insertion of the clip into the chamber defines the prong-receiving shape of the clip, and presses the bow 5 of the clip against the conductor wire.

In Fig. IV of the drawings the prong E of an attachment plug is shown inserted into the prongreceiving space 8 between the leaves 2 and 3 of the contact clip. This insertion has forced bent portion 4 of leaf 2 outwardl firmly to bear against wall 20 of the receptacle chamber, and has forced leaf 3 away from leaf 2. Resilient wing 1 at the outer edge of leaf 3 is deflected against wall 30 of the chamber and exerts resilient pressure directed radially inward of the wireembracing region 5 of the leaf 3, to urge it against the conductor wire B more forcefully to engage the wire. Thus, the insertion and withdrawal of the prong of the attachment plug causes a dispersed distribution of tension or release of tension throughout the body of the contact clip. This means that no line or zone in the contact clip assumes an undue proportion of the burden of resilient deformation, and the useful life of the contact clip is greatly prolonged. The engagement between the contact clip and the conductor wire being a yielding one, when a plug prong is inserted and withdrawn there is a slight relative wiping movement between their contact surfaces which serves to keep those surfaces bright and untarnished and to insure the continuance of good electrical contact between them.

It is a surprising discovery that the contact between the prongs of an attachment plug and conductor wires through the contact clips resiliently engaged with the wires gives better electrical contact than is obtained by binding screws or by welding even in the most perfect condition of the two last named modes ofattachment. Comparative tests were made with a binding screw receptacle accepted as a standard high quality receptacle, and with a welded clip made in accordance with the applicant's prior Patent No. 2,119,777. In these tests, using the same attachment plug, the resistance between the wire at the entering side of the receptacle and at the leaving side of the attachment plug was measured. With the engagement of contact clip and conductor wire in accordance with this invention, the resistance was one-fourth that existing in the receptacle in which the attachment was by a binding screw and plate connection between the conductor wire and the contact clip, and was onehalf that existing at a receptacle in which the contact clips were attached to the conductor wire by good welded integration.

The conductivity advantage of the disclosed structure is additional to the various installation advantages which have been indicated above. It is obvious that as to those advantages the yielding engagement of the contact clips with conductor wires gives the flexibility in installation obtainable with receptacles utilizing binding screws conjointly with the advantage possessed by the welded contact clips in being accommodated to receptacles of small external dimensions and simple structure which provide all required insulation for the assembly, and the advantage of eliminating in the field a connecting operation which may be imperfectly performed. Also by use of my contact clip the connection at any receptacle in a wiring installation may be a terminal connection for that pair of conductor wires. or it may be a connection made without splicing at any point along extended reaches of the wires. In the latter case it allows a choice of positioning auaeoe for the receptacle which is not obtainable with the factory welded integration of contact clips and conductor wires.

My disclosed contact clip is usable with advantage to replace the conductor wires of multiple outlet duct in which the clips are Welded. soldered or otherwise directly bonded to the conductor wires. Even in such association it presents increased flexibility in that receptacles may be placed anywhere along the length of the duct in installation, since predetermined spacing of the contact clips to define the positions of the receptacles is eliminated. Whereas it is an important incident of my yieldingly engaged contact clips that they may be used in receptacles of restricted size without a size requirement other than that sufiicient spacing to match the standard spacing between the prongs of an attachment plug be provided, it may be used in. receptacles of any desiredsize or ornamental shape. Also, if so desired, the minimum size receptacles shown in Figs. V and VI may be used and inserted in any desired mounting structure. Of these receptacles, the single-outlet receptacle F of Fig. V is of the sort which is adapted particularly to installation in numbers and in spaced relation in the housing of a multiple outlet duct, but which is also adapted to installation as an isolated outlet. The receptacle G of Fig. VI isa duplex receptacle usable either simply as an outlet or as a terminal connector in an extended circuit.

A preferred arrangement of my contact clips for association in a duplex receptacle is shown in Fig. VI in assembled relation with the duplex receptacle G shown therein. This duplex contact clip structure is formed of two clips A electrically connected by a longitudinally extended bar 9 which is integral with the flat portions of the leaves ill of both clips. Save for their electrical interconnection, the clips A are identical with the contact clips A shown in preceding figures of the drawings.

It is of course possible to equip a duplex receptacle with four individual and unconnected contact clips A if continuous conductor wires be engaged by both clips. If, however, the contact clips be interconnected in longitudinal pairs by suitable electrical connection of which the integral bars 9 are a preferred example, theutility of the receptacle is increased in the manner shown in Fig. VI. As therein shown, conductor wires .8, shown in full lines lead to the contact clips at one outlet of the duplex but are not continued to the clips at the other outlet. Without more, both outlets of the duplex are live and electrical connection may be made at either of them by inserting the prongs of an attachment plug. In order to continue the circuit to another receptacle, it is necessary merely to engage the bared ends of two other conductor wires B (shown in broken lines) with clips at the second outlet. The receptacle thus serves both as a duplex outlet and as a terminal connector, and performs the latter function without detracting in any way from its effectiveness in providing two outlets within the receptacle structure. I

I claim as my invention:

1. In combination with aconductor wire and a chambered insulating receptacle; a resilient light-gauge contact clip primarily of U-shape having an open end adapted to receive the prong of an attachment plug between its leaves. one leaf of the said clip at its end being outwardly deflected away from the prong-receiving cavity formed by the leaves of the clip to contact one wall of said receptacle chamber. a resilient structure at the free end of the other leaf of the clip reversely curved outwardly and inwardly to provide a bow-spring yieldingly receiving and embracing said conduotor wire in unbonded en-' gagement, and a resilient end element extended outwardly from the said reversely curved structure of the leaf to be tensioned by contact with the opposite wall of said receptacle chamber by compressive insertion of the contact clip thereinto.

2. In combination with a conductor wire and a chambered insulating receptacle, a resilient light auge contact clip primarily of U-shape having an open end adapted to receive the prong of an attachment plug between the leaves of the clip, the free ends of both leaves being adapted resiliently to engage opposite walls of said receptacle chamber in compressive insertion of the clip thereinto, a resilient structure at the free end of one of the said leaves reversely curved outwardly and inwardly with respect to the prongreceiving cavity of the clip to provide a bowspring yieldingly. receiving and embracing said conductor wire in unbonded engagement, and a resilient end element extended outwardly from thesaid reversely curved structure of .the said leai to be tensioned by pressure against one wall of said receptacle chamber when the contact clip is inserted thereinto.

3. In combination with a conductor wire and a chambered insulating receptacle, a resilient light gauge contact clip primarily of U--shape having an open end adapted to receive the prong of an attachment plug between the leaves of the clip,

the free ends or both leaves resiliently engaging opposite walls of said receptacle chamber in compressive insertion of the clip thereinto, the free end of one leaf being formed to embrace and resiliently embracing a conductor wire in unbonded engagement therewith and having an extension projected angularly outward with. respect to the prong-receiving cavity of the clip to be tensioned by pressure against one wall oi said receptacle chtamber when'the contact clip is inserted therein o.

4. In combination with a conductor wire and a chambered insulating receptacle, a resilient light gauge contact clip primarily of U-shape having an open end adapted to receive the prong of an attachment plug between the leaves of the clip, the free ends of both leaves resiliently engaging opposite walls of said receptacle chamber in compressive insertion of the clip thereinto, one of the said leaves between its wall-contacting end and its prong-receiving reach being reversely curved outwardly and inwardly with respect to the prong-receiving cavity of the clip to provide a bow-spring yieldingly receiving and embracing a conductor wire in' unbonded engagement. i

5. In a receptacle for making electrical contact with the prongs of an attachment plug the combination of a receptacle structure having therein a chamber with opposed insulating walls with a resilient contact clip primarily of U-shape having an open end adapted to receive the prong of an attachment plug between the leaves of the clip yieldingly engaged in the said receptacle chamber, said contact clip having one leaf thereof outwardly deflected away from the prongreceiving cavity formed by the leaves of the clip to contact one wall or the receptacle, a resilient structure at the free end of the other leaf of the clip reversely curved outwardly and inwardly to provide a bow-spring formed to receive and embrace a conductor wire oi circular cross-section in unbonded resilient engagement therewith, and a resilient end element extended outwardly from the said reversely curved structure of the leaf into contact with and compressively tensioned against the opposite wall of the said receptacle chamber.

6. In a receptacle for making electrical contact with the prongs of an attachment plug the combination of a receptacle structure having therein a chamber with opposed insulating walls with a resilient contact clip primarily of U-shape having an open end adapted to receive the prong of an attachment plug between the leaves of the clip compressed in said chamber, the free ends oi both leaves yieldingly engaging the opposite walls of the receptacle chamber under the compression of said clip in said chamber, and the free end of one leaf being formed to receive and embrace a conductor wire of circular cross-section in resilient unbonded engagement therewith and having an extension projected angularly outward with respect to the prong-receiving cavity of the clip to be further tensioned against one wall of the receptacle chamber when the contact clip is inserted thereinto.

7. In a receptacle for making electrical contact with the prongs of an attachment plug the combination of areceptacle structure having therein a chamber with opposed insulating walls with a resilient contact clip primarily of U-shape having an open end adapted to receive the prong of an attachment plug between the leaves of the clip compressed in said chamber, the free ends of both leaves yieldingly engaging the opposite walls of the receptacle chamber under the compression of said clip in said chamber, one of said leaves between its wall-contacting end and its prong-receiving reach being reversely curved outwardly and inwardly with respect to the prongreceiving cavity of the clip to provide a bowclip compressed in said chamber, the free ends Number of both leaves yieldingly engaging the opposite walls of the receptacle chamber under the compression of said clip in said chamber, a leaf of said contact clip between its wall-contacting end and its prong-receiving reach being reversely curved outwardly and inwardly with respect to the prong-receiving cavity of the clip to provide .a bow-spring formed to receive and embrace a conductor wire of circular cross-section in unbonded resilient engagement therewith, and an extension of the free end of a leaf of said contact clip projected outwardly with respect to the prong-receiving cavity of the clip in relative position to be further tensioned against the wall of the chamber on insertion of an prong between the leaves of the said clip.

MARTIN M. CLAYTON.

REFERENCES CITED The following references file of this patent:

UNITED STATES PATENTS Name Date Ball Sept. 29, 1908 Slade Apr. 29, 1930 Beersman Mar. 2, 1937 Clayton June 7, 1938 Abbott Aug. 27, 1940 Penfold May 11, 1943 are of record in the attachment plug 

